The cold low-pressure system developed over the Pacific Northwest Tuesday. The system moved south into central California Wednesday before scattered light showers arrived in Southern California Wednesday morning.

"It's very unusual for this time of year," said NBC4 forecaster Elita Loresca. "We'll see more widespread activity as we continue through the day."

Light rain was reported early Wednesday in the San Fernando Valley, Hollywood and other locations. By mid-day, light showers moved across a large swath of the region, including Pasadena, Pomona, Riverside and the Antelope Valley.

In a statement issued Wednesday morning, the Los Angeles County Sheriff's Department warned motorists that the first rain of the season can cause major problems when oils in the road are brought to the surface.

Cool, wet conditions are expected through Thursday. High temperatures will be in the 70s and mid-60s and measurable rainfall is possible for most of Los Angeles County.

Extreme Weather

In LA County mountain areas, light snow is possible at higher elevations Wednesday night, according to the National Weather Service. Most areas will receive no more than a tenth of an inch of rain, but more than a quarter of an inch could fall in the San Gabriel Mountains and the foothills, according to the NWS.

High winds are likely in some mountain and desert areas. Gusts might reach 50 to 65 mph.

Some of the region's coolest temperatures will be in Riverside County, where temperatures might drop into the 30s in mountain areas. Rainfall is expected to range from one to two-tenths of an inch in valleys and a quarter to three-quarters of an inch in the mountains.

A wind advisory was issued for the mountains and Coachella Valley from 5 p.m. Tuesday to 5 a.m. Wednesday.

"The winds will make driving difficult, especially for motorists with high profile vehicles," an NWS advisory said. "Watch for broken tree limbs and downed power lines."

The snow level might drop to 5,500 to 6,000 feet Wednesday night through early Thursday.

Areas above 6,000 feet will be under a winter weather advisory for from noon to 10 p.m. Wednesday, according to the Weather Service. Two to four inches of snow accumulation is possible above 6,000 feet and local amounts of four to eight inches were possible above 7,500 to 8,000 feet.